Aggregate: Medium, usually gravel, that is about the same size and used for the inert hydroponic medium.

Alkaline: Refers to soil with a high pH. Any pH over 7 is considered alkaline.

All-purpose (General-purpose) fertilizer: A balanced blend of N-P-K. All-purpose fertilizer is used by most growers in the vegetative growth stage. Many All-purpose fertilizers also contain secondary and trace elements.

Amendment: Substance used to change soil texture. Amendments can be organic or mineral.

Ampere (amp): The unit used to measure the strength of an electric current. A 20-amp circuit is overloaded when drawing more than 17 amps.

Annual: A plant that normally completes its entire life cycle in one year or less, marijuana, marigolds and tomatoes are examples of plants grown as annuals.

Arc: Luminous discharge of electricity (light) between two electrodes.

Arc tube: A quartz container for luminous gases also houses the arc in HID lights.

Auxin: Classification of plant hormones. Auxins are responsible for foliage and root elongation.

Carbon dioxide (CO2): A colorless, odorless, tasteless gas in the air necessary for plant life. Cannabis can process up to 1500 ppm (parts per million) of CO2 but there is only 350 ppm that naturally occurs in the air.

Companion planting: Planting garlic, marigolds, etc., along with other plants to discourage insect infestations. Companion planting can be beneficial over a long term.

Compost: A mixture of decayed organic matter high in nutrients. Compost must be at least one year old. When compost is too young decomposition uses nitrogen. Once left to compost for a few months compost releases nitrogen.

Core: The transformer in the ballast is referred to as a core in HID lighting systems.

Cotyledon: Seed leaves, first leaves that appear on a plant.

Cross-pollinate: Pollinate two plants having different ancestry.

Crystal: (1) Appearance resin has when found on foliage. (2) Fertilizers many times come in soluble crystals.

Salt: Crystalline compound that results from improper pH or toxic buildup of fertilizer. Salt will burn plants, preventing them from absorbing nutrients. Mineral salts-nutrients used to supply elements in hydroponic formulas.

Seal-a-meal: Airtight sealer for plastic baggies used to seal in freshness of pungent marijuana.

Secondary nutrients: Calcium (Ca) and magnesium (Mg).

Seed: The mature, fertilized, ovule of a pistilate plant, containing a protective shell, embryo and supply of food: A seed will germinate and grow, given heat and moisture.

Short circuit: Condition that results when wires cross and form a circuit. A short circuit will blow fuses.

Sinsemilla: Two Spanish words: sin = without, semilla = seed combined into one word by Americans: Sinsemilla describes flowering female cannabis, that has not been fertilized.

Stagnant: Motionless air or water. Water must be drained and not become stagnant for healthy marijuana growth.

Stamen: Male, pollen producing.

Starch: Complex carbohydrate. Starch is manufactured and stored food.

Sterilize: Make sterile (super-clean) by removing dirt, germs and bacteria.

Strain: (l) Ancestry, lineage, phenotype, a particular type of marijuana having the same characteristics. (2) To abuse a plant by withholding nutrients, water, etc.

Stroboscopic effect: A quick pulsating or flashing of a lamp.

Stress: A physical or chemical factor that causes extra exertion by plants. A stressed plant will not grow as well as a non-stressed plant.

Stomata: Small mouth-like or nose-like openings (pores) on leaf underside, responsible for transpiration and many other life functions. The millions of stomata must be kept very clean to function properly.